Cutting energy bills in a small factory: where to start

Why a small saving is worth more than it looks

An energy saving recurs every year and goes straight to profit. For a firm with a 5% profit margin, every pound saved on energy adds as much profit as twenty pounds of extra sales.

Using less energy also means lower emissions, which is the figure customers, lenders and public buyers ask about in questionnaires and tenders. One set of meter readings serves both purposes.

The building: heating, doors and lighting

The longer the heating runs and the higher the thermostat, the higher the bill. Timers and thermostats are often installed and then forgotten. Walk round the site and check that:

• Timers show the right date and time, and allow for shift patterns and holidays.
• Stores and corridors are heated less than offices.
• Thermostats are not placed near heat sources, draughts or direct sun.
• Loading bay doors are kept closed, or fitted with PVC strip curtains.
• Heating is not fighting air conditioning in the same space.
• Lights in stores and toilets switch off when nobody is there, and external lights run on timers or sensors.

The DECC guide gives a sense of scale. Heating costs rise by around 8% for every 1°C increase, up to 30% of heating costs can be saved by stopping cold air getting into the building, and occupancy sensors alone could cut lighting energy by 30%.

Motors and drives

Motors drive the pumps, fans, conveyors and machine tools on a factory floor. Many run at full speed when they do not need to, or when nothing is being made.

• Switch motors off when machines are idle, including at breaks.
• Make sure someone knows what every large motor does and how long it runs.
• Check belts, bearings and alignment in routine maintenance.
• Control fan and pump flow with variable speed drives, not throttling valves or dampers.
• Replace failed motors with high-efficiency ones sized for the load they now drive, rather than rewinding them by habit.

Motor speed has a large effect on energy use. According to DECC, reducing the speed of a motor by 20% can halve its energy use. The effect is largest on fans and pumps, so one that runs slower for part of the day can cost much less to run.

Compressed air

Compressed air is convenient, but it is one of the most expensive ways to use energy on site. DECC's guide says compressed air can account for 10% of an energy bill, and half of that can be due to leaks. An idling compressor still uses 20 to 70% of its full-load power, and reducing air pressure by 10% can save 5% of the energy.

• Find and fix leaks regularly. Listen for them when the site is quiet.
• Switch compressors off when production stops.
• Generate air at the lowest pressure the equipment needs.
• Use a brush or a fan for cleaning and cooling instead of compressed air.
• Isolate branches of the pipework that are no longer used.
• Recover heat from the compressor where there is a use for it.

DECC's guide includes the case of a small printing machine manufacturer that fixed nine leaks in its compressed air system and cut its emissions by 7 tCO₂e a year.

Measure before and after

A saving you can show is worth more than one you describe. Customers and funders ask to see the evidence, so set up the measurement before you change anything.

1. 1Set a baselineKeep a full year of bills and meter readings for each site.
2. 2Meter the largest usersFit sub-meters or clamp-on loggers on compressors, ovens and large motors, so you can see their share and the effect of each change.
3. 3Log each changeNote what you changed and the date you changed it.
4. 4Compare like with likeCompare the same months at similar production levels, not a quiet summer with a busy winter.

For the steps that do cost money, options include your own cash, loans and asset finance, leasing, and grants when schemes are open. The Annual Investment Allowance and full expensing reduce the tax cost of qualifying equipment. Check current grants with your local Growth Hub, Business Energy Scotland, Business Wales or Invest Northern Ireland, because terms change often.

How ESGen helps

The ESGen platform records your sites and meters and turns electricity, gas and fuel use into kWh and Scope 1 and 2 emissions with the DESNZ factors, with the bill behind each figure. That gives you a measured baseline and a year-on-year comparison you can show a customer. Figures are entered from your bills and meter readings; the platform works in energy and emissions, not in pounds.

Energy audits and equipment installation are outside our service. Where a customer or tender asks for evidence, our team can turn your baseline into questionnaire answers or a Carbon Reduction Plan. See how we work with manufacturers.

To see a site baseline built from example bill data, book a demo.